Best Time to Fly SFO to ONT: On-Time Stats by Hour & Airline
San Francisco International → Ontario International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 76.4% of San Francisco (SFO) to Ontario (ONT) flights arrived on time (1,310 scheduled flights). That is 1.2 points below the national average of 77.6%.
United Airlines was the most punctual of the 3 airlines on the route at 81.4%, while Frontier Airlines trailed at 56.3%.
April has been the best month (88% on time) and Thursday the weakest day of the week (76%).
0.9% of flights were cancelled, versus 1.8% nationally.
SFO to ONT on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| United Airlines | 81.4% | 52 min | 0.3% | 982 |
| SkyWest Airlines | 68.2% | 73 min | 2.3% | 132 |
| Frontier Airlines | 56.3% | 94 min | 3.1% | 196 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly SFO to ONT
On-time arrival % by scheduled departure hour (local time), 2,899 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | Limited data | 9 | |
| 6am–7am | Limited data | 3 | |
| 7am–8am | Limited data | 15 | |
| 8am–9am | 90.6% | 0.3% | 353 |
| 9am–10am | 78.0% | 1.8% | 111 |
| 10am–11am | 83.3% | 0.0% | 372 |
| 11am–12pm | 69.1% | 0.0% | 194 |
| 12pm–1pm | Limited data | 21 | |
| 1pm–2pm | 76.9% | 3.1% | 161 |
| 2pm–3pm | Limited data | 3 | |
| 4pm–5pm | 80.2% | 1.3% | 712 |
| 5pm–6pm | 79.3% | 3.3% | 60 |
| 6pm–7pm | 87.7% | 0.0% | 65 |
| 7pm–8pm | 92.9% | 0.0% | 99 |
| 8pm–9pm | Limited data | 4 | |
| 9pm–10pm | 76.4% | 0.6% | 536 |
| 10pm–11pm | 48.2% | 2.8% | 143 |
| 11pm–12am | 91.9% | 2.6% | 38 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on SFO to ONT
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | 81.2% | -0.5 pts | 0.0% | 69 |
| Christmas & New Year (Dec 20 - Jan 3) | 65.4% | -16.3 pts | 4.5% | 112 |
| Summer peak (Jun 15 - Aug 15) | 71.7% | -10.0 pts | 0.4% | 462 |
| All other days | 81.7% | — | 0.9% | 2,256 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).